1. Field of the Invention
The present invention relates generally to part fabrication processes, and more particular to a fabrication process for making complex composite parts such as marine propeller blades.
2. Description of the Prior Art
Complex parts such as marine propulsors/propellers are designed in accordance with well known aero/hydrodynamic theory. The first object of design in both aero and hydrodynamic scenarios is to provide the desired lift force suitable to propel or thrust the body forward. The underlying principles are the same for both the aero and hydrodynamic scenarios. However, operational constraints placed on marine propulsors/propellers challenge designers to meet conflicting physical constraints. This is especially true in the case of submersible vehicles. The most important of these physical constraints include design features/materials that achieve:
high efficiency to conserve propulsive energy, fuel, powerplant size and weight; PA0 high thrust to provide a top speed which does not waste propulsor power; PA0 high strength to prevent distortions and breakage, while minimizing size and weight; PA0 low vibration and noise to minimize the amount of acoustic power radiation that is transmitted into the water or to the attached vehicle which is being propelled; PA0 low cost of manufacture and maintenance; and PA0 high resistance to external and internal corrosion and chemical attack due to the harsh nature of the marine environment.
In particular, propulsors/propellers that are to produce a high thrust at a high efficiency while presenting a low noise signature pose the greatest challenge because of the vastly conflicting design/manufacturing constraints. For example, the most efficient blade design may be too large/heavy to meet the desired strength characteristics needed to carry required loads at acceptable amounts of distortion. The most cost effective design may be too imprecise to meet the geometric specifications, thereby losing efficiency. The quietest design may not be possible because a single material is not available or is not practical for manufacture of either the scaled, prototype, or manufacturing phases. Thus, the design of marine propulsors/propellers has advanced to the point of specifying not only a complex shape, but ideally a composite construction using multiple materials in order to best satisfy all of the design performance constraints. Unfortunately, many materials well suited for marine propulsor/propeller fabrication have little or no value in the ultimate part design. Similarly, at the other end of the spectrum, materials well suited for ultimate marine propulsor/propeller performance frequently tax the fabrication process in terms of complexity, time and/or expense.